Electronic interfaces are used ubiquitously to transfer information, generally in the form of analog and digital signals, between two or more functional blocks. Two common interface architectures are serial interfaces and parallel interfaces. In a digital application, a parallel interface generally refers to a multiline channel, each line capable of transmitting several bits of data simultaneously. Most commonly, personal computers have traditionally incorporated at least one parallel interface employing a parallel communications port (e.g., IEEE 1294, or similar). In contrast, a serial interface generally refers to a single channel capable of only transmitting one bit of data at a time.
The capabilities of a parallel interface, although having a higher bandwidth for transmission of signals, are often limited by signal integrity (SI) effects. Two factors which contribute to SI effects include, but are not limited to, coupling of signals (e.g., crosstalk), and simultaneous switching output (SSO) effects on power. Coupling of signals is generally an electromagnetic phenomenon (e.g., relating to spurious signals or signal components induced on a signal line by electromagnetic field interactions from another signal line). SSO noise, also known as ground bounce or power bounce, is typically a result of large instantaneous changes in current across the power/ground inductance of an integrated circuit. This potential problem becomes more serious as the number of active high-drive (e.g., low-voltage complementary metal-oxide-semiconductor (LVCMOS)) outputs on an integrated circuit device increases. In large field programmable gate arrays (FPGAs), for example, with several synchronous parallel interfaces this phenomenon can result in poor system performance and/or intermittent data errors.